Multiple filament incandescent lamp



1961 G. J. EDWARDS 2,997,616

MULTIPLE FILAMENT INCANDESCENT LAMP Filed Nov. 15, 1958 Invervtov: GeotiJEdwavds, 10 at: A?

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2,997,616 MULTIPLE FILAIVIENT IN CANDESCENT LAMP George J. Edwards,Painesville, Ohio, assignor to General Electric Company, a corporationof New York Filed Nov. 13, 1958, Ser. No. 773,769 3 Claims. (Cl.313-272) My invention relates generally to electric incandescent lamps,and more particularly to multiple filament lamps adapted to yieldseveral different levels of illumination. Still more particularly, theinvention relates tothe mount structure including a novel arrangement offilaments and supporting structure therefor.

It is an object of my invention to provide a novel arrangement orcombination of a pair of filaments which will provide a high over-allefiiciency of illumination together with over-all economy ofmanufacture. It is a further object to arrange the filaments and thesupporting structure therefor into a unit of sufficient compactness tofit through the constricted neck portion of the enclosing glass bulbwithout giving rise to problems of assembly in high-speed massproduction on automatic equipment or of arcing during operation of thelamp.

In accordance with one aspect of my invention, I utilize for the majoror higher wattage filament the recently marketed form of a helicalcoiled-coil disposed with its axis parallel to the longitudinal axis ofthe lamp bulb so as to be in a vertical position in either the base-downor base-up position of the lamp. For reasons not yet fully understood,the same filament will operate at higher efiiciency and for a longerlife in the vertical position than when it is horizontally disposed. Forthe minor or lower wattage filament, I employ a helical single coilformed to an arcuate shape. Although the coiled-coil filament is morecostly than a single coil filament, that factor is outweighed by theadvantage of higher efiiciency of light production when employed as themajor filament. However, a second or minor filament of coiled-coil typeis diflicult to mount vertically in automatic lamp making equipment, sothat the less costly single coil is advantageous as a minor filamentwhere efficiency is less'important since it is not used alone forreading or other difficult seeing tasks. Moreover, the combination of avertical coiled-coil filament and an arcuate single coil filament ismore eflicient over-all than, for example, two horizontally arrangedcoiled-coil filaments which would be easier to assemble on automaticequipment.

A further feature is the mounting of the arcuate single coil filament inclamping hooks on its lead-in wires in such a manner that the coilleaves the hook at an angle of about 90 from the hook axis in everyplane normal to the plane in which the U-shaped hook lies, whereby thecoil forms a smooth are between the lead wire tips with no sharp bendsat or near the hooks such as to cause non-uniform spacing of the coilturns with accompanying adverse effect on lamp life. This result isobtained by bending the upper ends of the lead-in wires so as to beinclined at an acute angle to the horizontal and to extend divergentlytoward the plane including the lead-in wires for the vertical filament,and terminating in hook portions lying in a plane including the saidbent upper ends of the lead-in wires, the arcuate filament being clampedat its ends in said hooks and lying in a plane inclined from thehorizontal and substantially normal to the said plane including saidbent upper ends of the lead-in wires. The resulting structure also hasthe advantage of compactness in lateral dimensions so as to fit into theconstricted bulb neck, while maintaining adequate spacing from thevertical major filament and its supporting structure to avoid arcing.

In accordance with a still further feature, the major vertical filamentand its supporting lead-in wires are in tes atent a substantiallyvertical plane which is preferably displaced from the axis of the lampin a direction opposite that at which is located the minor filament andits supporting lead-in wires, thereby to provide maximum spacing betweenthe filaments with minimized tendency to arcing and adequate room foraccess of machine tools for performing the assembly operation whilestill permitting the mount to fit through the neck of the lamp bulb.

Still further features and advantages of my invention will appear fromthe following detailed description of a species thereof and from thedrawing wherein:

FIG. 1 is an elevation of a lamp structure comprising my invention;

FIG. 2 is an elevation approximately at right angles to FIG. 1; and

FIG. 3 is a plan view of the lamp.

Referring to the drawing, the lamp comprises a gasfilled glass bulb orenvelope 1 which may be of conventional pear-shape and having aconstricted cylindrical neck portion 2 and an internal mount structureincluding a re-entrant glass stem tube 3 having a flared lower end 4(FIG. 1) sealed to the end of the neck portion 2. It will be understoodthat during the heating and sealing of the neck 3 to the flare 4, thelower end portion 5 of the bulb neck is further constricted by thesealing fires to join with the rim of flare 4.

The mount structure also includes a pair of tungsten wire filaments 6and '7 located at opposite sides of the bulb axis 8. The filament 6 is ahelical coiled-coil disposed longitudinally of the bulb, and thefilament 7 is a helical single coil bent to arcuate shape and lying in aplane at about 45 to the horizontal, the major filament 6 being ofhigher wattage than the minor filament 7, for example 100 watts and 50watts, respectively. The major filament 6 is mounted on and betweenlaterally extending end portions 9 and 10 of a pair of respectivelylonger and shorter lead-in wires 11 and 12 which lie approximately in avertical plane parallel to axis 8 and which have portions thereof sealedin two of the corners of a generally square compressed press or sealportion 13 at the upper end of the stem tube 3. The lead-in wires 11 and12 are supported or braced by respective anchor wires 14 and 15 loopedaround the lead-in wires at one end and having their other ends anchoredin a button 16 at the upper end of a glass arbor 17 extending upwardlyfrom the stem press 13 along the axis 8.

The minor filament 7 is mounted on a pair of lead-in Wires 18 havingportions thereof sealed in the other two corners of the stem press 13and extending upwardly in a generally vertical plane approximatelyparallel to the plane including the lead-in Wires 11 and 12 and on theopposite side of the axis '8 therefrom. The upper end portions or tips19 of the lead wires 18 are bent to be inclined upwardly at an acuteangle of about 45 to the horizontal and divergently toward the planeincluding lead wires 11 and 12, and terminate in U-shaped clamp or hookportions 20 lying in a plane including the said bent end portions ortips 19. The ends of the filament 7 are clamped in said hook portions 20so that. the filament coil 7 forms a smooth are between the tips of thelead Wires, and the end portions of the filament leave the hooks at anangle of about from the hook axis in every plane normal to the planeincluding the hooks and the tips 19.

The minor filament 7 is additionally supported by looped ends ofauxiliary support Wires 21 having their other ends anchored in the arborbutton 16. Depending upon the rating of the filament 7 and whether it ismade of heavier or finer wire, one or two supports 21 may be employed.The major filament 6 is also braced against vibration by an auxiliarysupport wire 22 which U is anchored in the button 16 and extendsvertically upward and thence laterally toward the midpoint of thefilament 6 where it terminates in a loop encircling the filament.

It will be observed that the lateral end portion 9 of lead wire 11 islonger than the corresponding end portion of lead wire 12 so that thefilament 6 is offset toward the shorter lead wire 12 and away from thelonger lead wire 11 to avoid arcing between the filament ti and thelonger lead wire 11. It will also be noted that the support wire 22 forfilament 6 is located in the space between the filaments 6 and 7, ratherthan at the outside of filament 6, to thereby permit a larger spacingbetween the filaments 6 and 7 and therefore less tendency to are, whilestill allowing room for the mount to fit into the bulb neck 2. When thesupport wire 22 is located at the outside of filament 6 and too close tothe filament, arcing occurs between the filament and the support wire,and if the support wire is moved farther away from the filament, thenthe lateral dimensions of the mount are too great to fit through thebulb neck.

The shape of the tips 19 of lead wires 18 also provides severaladvantages including the avoidance of sharp bends in the filamentadjacent the joints to the lead wire tips, as well as compactnesswithout arcing. Thus, the filament 7 is thereby located in a planeinclined to the horizontal rather than in a horizontal plane so that itfits readily into the bulb neck. If the lead tips 19 were to be bentinto a horizontal plane, it would bring the filament 7 too close to thefilament 6 and increase the tendency to are between the filaments unlessthe lateral dimensions and spacing were increased to an extent such thatthe mount would not enter the bulb neck. Also, if the lead tips 19 wereto be flared out only in the plane of the lead wires 18 (i.e. not benttoward the plane of filament 6 and lead wires 11 and 12.), then the leadwires 18 would have to be too close together and too close to thesupport wires 21 to avoid arcing. Furthermore, placing the majorfilament 6 in the bulb and mount axis 8, and the minor filament '7 in ahorizontal plane and encircling the filament 6, results in violentarcing. 'It is therefore believed to be apparent that the structuredisclosed herein possesses the advantages of high over-all efiiciency,economy of manufacture on automatic equipment and necessary compactnesstogether with freedom from arcing.

The lamp may be provided with a conventional base attached to the bulbneck and comprising a screw-threaded metal shell 23 having at its end aninsulating web 24 of glass or organic plastic and having aflixed theretoan end contact eyelet 25 and an intermediate ring-shaped contact 26. Thelead wire 12 and the opposed lead wire 18 (the one at the left inFIG. 1) may be connected to the shell 23, lead wire 11 to the endcontact 25, and the other lead wire 18 to the intermediate contact Q6,whereby the filaments 6 and 7 may be operated independently orsimultaneously in parallel to give three different levels ofillumination.

What I claim is new and desire to secure by Letters Patent of the UnitedStates is:

1. A multiple filament electric incandescent lamp mount comprising astem having a vertical axis, a first pair of lead-in wires sealed in andextending upwardly from said stem in spaced relation and approximatelyin a first vertical plane to one side of said stem axis, said leadinwires being of difierent lengths and having their inner ends extendinglaterally and terminating in vertical alignment one above the otherapproximately within said vertical plane, a coiled-coil filamentextending vertically between and connected at its ends to the terminalportions of said inner ends of the respective lead-in wires, a secondpair of lead-in wires sealed in and extending upwardly from said stem inspaced relation and substantially in a second generally vertical planelocated to the side of said stem axis opposite that at which is locatedthe said first plane containing said first pair of lead-in wires, saidsecond pair of lead-in wires having upper end portions bent generallytoward said first plane to be inclined upwardly at an acute angle to thehorizontal and divergently away from each other and terminating in hookportions lying in a plane including said upper end portions, and asingle coiled filament of arcuate fornr having its ends clamped in saidhook portions and lying in a plane substantially normal to the saidplane includ ing said upper end portions so that said filament extendsfrom the said hook portion at an angle of about from the axis of saidhook portion in planes normal to the said plane in which said hookportions lie whereby the filament forms a smooth are between said hookportions.

2. A multiple filament electric incandescent lamp mount comprising astem having a vertical axis and including an arbor extending axially andupwardly therefrom, a first pair of lead-in wires sealed in andextending upwardly from said stem in spaced relation and substantiallyin a first vertical plane to one side of said stem axis, said lead-inwires being of difierent lengths and having their inner ends extendinglaterally and terminating in vertical alignment one above the otherapproximately within said vertical plane, a coiled-coil fila" mentextending vertically between and connected at its ends to the terminalportions of said inner ends of the respective lead-in wires, a secondpair of lead-in Wires sealed in and extending upwardly from said stem inspaced relation and substantially in a second generally vertical planelocated to the side of said stem axis opposite that at which is locatedthe said first plane contain ing said first pair of lead-in wires, saidsecond pair of lead-in wires having upper end portions bent generaiytoward said first plane to be inclined upwardly at an acute angle to thehorizontal and divergently away from each other and terminating in hookportions lying in a plane including said upper end portions, so thatsaid filament extends from the said hook portion at an angle of about 90from the axis of said hook portion in planes normal to the said plane inwhich said hook portions lie whereby the filament forms a smooth arebetween said hook portions and a single coiled filament of area-- ateform having its ends clamped in said hook porti s and lying in a planesubstantially normal to the said plane including said upper endportions, a support wire anchored in the upper end of said arbor andextending upwardly therefrom in the space between said filaments andthence laterally toward and embracing the midpoint of said coiled-coilfilament, and at least one other support wire anchored in the upper endof said arbor and extending to and embracing said single coiled filamentat a point intermediate its ends.

3. A multiple filament electric incandescent lamp mount comprising astem having a vertical axis, a first pair of lead-in wires sealed in andextending upwardly from said stem in spaced relation and substantiallyin a first vertical plane to one side of said stern axis, said lead-inwires being of different lengths and having their inner ends extendinglaterally and terminating in vertical alignment one above the otherapproximately within said vertical plane and nearer the shorter of saidlead-in wires, a coiled-coil filament extending vertically between andconnected at its ends to the terminal portions of said inner ends of therespective lead-in wires, a second pair of lead-in wires sealed in andextending upwardly from said stem in spaced relation and substantiallyin a generally vertical second plane located to the side of said stemaxis opposite that at which is located the said first plane containingsaid first pair of lead-in wires, said second pair of lead-in wireshaving upper end portions bent generally toward said first plane to beinclined upwardly at an acute angle to the horizontal and divergentlyaway from each other and terminating in hook portions lying in a planeincluding said upper end portions, and a single coiled filament ofarcuate form having its ends clamped in said hook portions and lying ina plane substantially normal to the said plane including said upper endportions so that said filament extends from the said hook portion at anangle of about 90 from the axis of said hook portion in planes normal tothe said plane in which said hook portions lie whereby the filamentforms a smooth are between said hook portions.

References Cited in the file of this patent UNITED STATES PATENTS DakeJan. 12, 1926 Melish Mar. 17, 1931 Sperti Mar. 24, 1936 Wengel June 9,1936 Witbeck June 24, 1941 Kurlander May 18, 1948

